In coal gasification and particularly in connection with finely divided coal, the procedure using a down flow generator having a bottom exit has encountered problems with the slag and fly ash that develops. Particularly in regard to the liquid slag, it tends to build up and clog the exit throat. Such a combustion chamber has a refractory lining, and in the previous structures it was constructed with the bottom exit being made into a funnel shape through which the hot gases and fly ash including liquid slag etc, must pass including the throat portion of such funnel exit. However, it has been found that such prior structure tended to recirculate the hot gases and fly ash at the bottom of the combustion chamber. Also, the gas velocity profile through the exit throat was parabolic in shape, i.e. lower velocity flow would develop near the sides of the throat with maximum velocity at the center. Such a velocity profile does not help to drain the slag, which being liquid tends to run along the walls of the throat at a lower velocity than the gas passing through.
The problem with removing non-carbonaceous residue that is produced during gasification in reactor apparatus, has been recognized in a U.S. Pat. No. 4,022,591, May 10, 1977 issued to Staudinger as patentee. However, the structure proposed in that patent deals with a generator having upwardly directed reactant supply tubes. And, those tubes are centrally located beneath an exit throat at the bottom of the generator. That arrangement was also concerned with the very high temperatures in the reactor and consequent difficulties with the reactor inlet tubes or the like. In addition, the structure of that patent creates a counter flow of coal and reactant gases to the by-product ash being removed.